code: def test_amp_ddp(
      cuda_count_2, strategy, devices, custom_plugin, plugin_cls
  ):
      plugin = None
      precision = None
      if custom_plugin:
          plugin = plugin_cls("16-mixed", "cpu")
      else:
          precision = "16-mixed"
      trainer = Trainer(
          fast_dev_run=True,
          precision=precision,
          accelerator="gpu",
          devices=devices,
          strategy=strategy,
          plugins=plugin,
      )
      assert isinstance(trainer.precision_plugin, plugin_cls)
  
imports: import os
  import re
  from unittest import mock
  import pytest
  import torch
  from lightning.pytorch import Trainer
  from lightning.pytorch.demos.boring_classes import BoringModel
  from lightning.pytorch.plugins import MixedPrecision
  from torch import Tensor
  from tests_pytorch.helpers.runif import RunIf
label_desc: Use image node_id 1 for calling a global function with example usage: test_amp_ddp(cuda_count_2, strategy, devices, custom_plugin, plugin_cls) without return types